How to I cut a specific part of an object in order to have 2 separate objects?
I would try to press "L" key in edit mode with cursor over some part of the model. This selects "Island" in case the model is not merged together. if it is merged, you can try to select one face somewhere in the middle of the part you want to separate then press "ctrl +" to start adding faces to your selection. To separate your selection you can use "P" key then "separate selection"